Invariance under quasi-isometries of subcritical and supercritical behaviour in the Boolean model of percolation

In this work we study the Poisson Boolean model of percolation in locally compact Polish metric spaces and we prove the invariance of subcritical and supercritical phases under mm-quasi-isometries. In other words, we prove that if the Poisson Boolean model of percolation is subcritical or supercritical (or exhibits phase transition) in a metric space M which is mm-quasi-isometric to a metric space N, then these phases also exist for the Poisson Boolean model of percolation in N. Then we apply these results to understand the phenomenon of phase transition in a large family of metric spaces. Indeed, we study the Poisson Boolean model of percolation in the context of Riemannian manifolds, in a large family of nilpotent Lie groups and in Cayley graphs. Also, we prove the existence of a subcritical phase in Gromov spaces with bounded growth at some scale

Random cover times using the Poisson cylinder process

In this paper we deal with the classical problem of random cover times. We investigate the distribution of the time it takes for a Poisson process of cylinders to cover a set $A \subset \mathbb{R}^d.$ This Poisson process of cylinders is invariant under rotations, reflections and translations, and in addition we add a time component so that cylinders are "raining from the sky" at unit rate. Our main results concerns the asymptotic of this cover time as the set $A$ grows. If the set $A$ is discrete and well separated, we show convergence of the cover time to a Gumbel distribution. If instead $A$ has positive box dimension (and satisfies a weak additional assumption), we find the correct rate of convergence

Progetto di una cella a doppia curvatura in vetro ed acciaio ed analisi di un caso studio

Il progetto di tesi è finalizzato allo sviluppo di una cella a doppia curvatura in vetro e acciaio funzionale all’applicazione su superfici vetrate a forma variabile. La tesi si sviluppa su due livelli: dapprima si analizza il comportamento strutturale della cella per poi sviluppare un caso studio costituito da una copertura a doppia curvatura. Nello studio della curvatura a freddo del vetro, al fine di ottenere una superficie a doppia curvatura (paraboloide iperbolico) non è possibile prescindere da analisi non lineari, le quali consentono di cogliere notevoli incrementi dello stato tensionale rispetto al modello lineare; un fenomeno di instabilità geometrica è dimensionante per la massima deformazione che può raggiungere il pannello in vetro. Mediante analisi non lineari multistep è stato analizzata la mutua interazione tra telaio in acciaio e pannello vetrato, valutando la migliore soluzione del telaio per rendere la cella “autoportante”. Attraverso il caso studio è stato possibile valutare le possibilità di assemblaggio delle celle: unendo tra loro celle con diverso grado di deformazione è possibile discretizzare una superficie a doppia curvatura, minimizzando lo scostamento con la superficie di base. L’analisi di tale copertura ha evidenziato come la curvatura a freddo, impegnando il vetro per quasi il 60% della sua resistenza, sia fortemente limitante nelle verifiche strutturali del vetro

Institutional contexts and school improvement in Natural Sciences: The case of “Bicentennial Schools”

En Iberoamérica, la educación en Ciencias Naturales ha sido declarada prioritaria en las últimas décadas. Sin embargo, evaluaciones internacionales y nacionales demuestran resultados alarmantes en esta área, particularmente en Latinoamérica. En respuesta, surgieron allí diversas iniciativas de mejora, aunque no siempre fueron evaluadas sistemáticamente. Este trabajo analiza el caso de “Escuelas del Bicentenario”, un programa de mejora escolar en el que participaron 132 escuelas primarias argentinas de contextos vulnerables. Evaluamos la mejora de los aprendizajes en Ciencias de los alumnos de 4to grado, comparando su rendimiento al inicio y al final del programa. Luego, analizamos la variabilidad de los cambios observados por escuela y examinamos las características institucionales de las que obtuvieron los porcentajes más altos y más bajos de mejora. Para ello, analizamos los testimonios de los especialistas que trabajaron con sus docentes y directivos a través de entrevistas semiestructuradas y de relatorías mensuales. Nuestros resultados muestran una mejora significativa en el aprendizaje de los alumnos en general, con una importante variabilidad entre escuelas. El análisis cualitativo indica que el equipo directivo fue fundamental en las diferencias de crecimiento encontradas, cuyo rol fue clave para sostener las acciones de capacitación docente y mejora impulsadas por el programaScience is considered a priority subject in education systems across Iberoamerica. However, international and national examinations have shown alarming results on students´ achievement levels in this area, especially in Latin America. Consequently, many school improvement programs were designed and implemented in the region, but only occasionally assessed. This paper presents the case of “Bicentennial Schools”, a school improvement program that involved 132 primary schools from vulnerable socioeconomic contexts in Argentina. We analyse the impact of the program by comparing the results of 4th grade students´ tests before and after the intervention. We also assess the program´s impact variability and examine the institutional characteristics of the highest and lowest performing schools. To do so, we analysed the teacher educators´ testimonies through semistructured interviews and their monthly work reports. Our findings show a significant improvement in the students´ performance in general, as well as an important variability in the program´s impact across schools. The qualitative analysis indicates that the principals´ role can explain this variation, as it constituted a key factor to sustain teacher training and the improvement efforts driven by the progra

Obesidad: un desafío para las políticas públicas

La obesidad es un problema médico que ha sido declarada epidemia mundial por la Organización Mundial de la Salud. El aumento de su prevalencia implica incrementos en los costos de los sistemas de salud, tanto en forma directa como indirecta, conjuntamente con un deterioro de la calidad de vida. Se vuelva un tema prioritario dentro de la agenda pública de los gobiernos. Las fallas de mercado presentes en el sector constituyen un argumento que justifica la intervención estatal. En función de ello, es que el objetivo del presente trabajo es analizar las fallas de mercado presentes en el sector y realizar una recopilación exhaustiva de las políticas públicas que han sido propuestas para el tratamiento y la prevención de la obesidad

Absence of liver steatosis in HIV-infected patients receiving tenofovir-containing regimen

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Reliable and Accurate CD4+ T Cell Count and Percent by the Portable Flow Cytometer CyFlow MiniPOC and \u201cCD4 Easy Count Kit-Dry\u201d, as Revealed by the Comparison with the Gold Standard Dual Platform Technology

An accurate and affordable CD4+ T cells count is an essential tool in the fight against HIV/AIDS. Flow cytometry (FCM) is the "gold standard" for counting such cells, but this technique is expensive and requires sophisticated equipment, temperature-sensitive monoclonal antibodies (mAbs) and trained personnel. The lack of access to technical support and quality assurance programs thus limits the use of FCM in resource-constrained countries. We have tested the accuracy, the precision and the carry-over contamination of Partec CyFlow MiniPOC, a portable and economically affordable flow cytometer designed for CD4+ count and percentage, used along with the "CD4% Count Kit-Dry"

A new Neandertal femoral diaphysis from Les Pradelles (Marillac-le-Franc, Charente, France)

Background and purpose: A femoral diaphysis of an adult Neandertal was discovered in 2010 at the site of Les Pradelles (Marillac-le-Franc, Charente, France) with occupation levels from MIS 4. We describe the Les Pradelles (LP) femoral diaphysis and discuss its morphometric characteristics in relation to Late Pleistocene diversity. Materials and methods: The comparative sample for the LP femur consists of Neandertals, Middle Paleolithic modern humans and European Upper Palaeolithic modern humans. Classical measurements (diameters) and cross-sectional geometric properties were studied at mid-diaphysis. The pattern of thickness variations was also analyzed. Results: Morphological aspects of this diaphysis clearly relate it to those of the Neandertals (anterior curvature, lack of pilaster, medial buttress). Exostoses near and on the linea aspera may be the consequence of a pathological bone reaction, with unknown cause. Cross-sectional geometric properties place the LP femur within the range of Neandertal variation. It presents, among other features, a greater amount of cortical bone in comparison tomodern human variability. The 3Dmodeling highlights a medial side with an important cortical thickness corresponding to the medial buttress. Conclusions: The LP femur provides additional data to our knowledge of MIS4 Neandertal variability, less well documented than those assigned to MIS5 and MIS3

CD4 cell count and the risk of AIDS or death in HIV-Infected adults on combination antiretroviral therapy with a suppressed viral load: a longitudinal cohort study from COHERE.

BACKGROUND: Most adults infected with HIV achieve viral suppression within a year of starting combination antiretroviral therapy (cART). It is important to understand the risk of AIDS events or death for patients with a suppressed viral load. METHODS AND FINDINGS: Using data from the Collaboration of Observational HIV Epidemiological Research Europe (2010 merger), we assessed the risk of a new AIDS-defining event or death in successfully treated patients. We accumulated episodes of viral suppression for each patient while on cART, each episode beginning with the second of two consecutive plasma viral load measurements 500 copies/µl, the first of two consecutive measurements between 50-500 copies/µl, cART interruption or administrative censoring. We used stratified multivariate Cox models to estimate the association between time updated CD4 cell count and a new AIDS event or death or death alone. 75,336 patients contributed 104,265 suppression episodes and were suppressed while on cART for a median 2.7 years. The mortality rate was 4.8 per 1,000 years of viral suppression. A higher CD4 cell count was always associated with a reduced risk of a new AIDS event or death; with a hazard ratio per 100 cells/µl (95% CI) of: 0.35 (0.30-0.40) for counts <200 cells/µl, 0.81 (0.71-0.92) for counts 200 to <350 cells/µl, 0.74 (0.66-0.83) for counts 350 to <500 cells/µl, and 0.96 (0.92-0.99) for counts ≥500 cells/µl. A higher CD4 cell count became even more beneficial over time for patients with CD4 cell counts <200 cells/µl. CONCLUSIONS: Despite the low mortality rate, the risk of a new AIDS event or death follows a CD4 cell count gradient in patients with viral suppression. A higher CD4 cell count was associated with the greatest benefit for patients with a CD4 cell count <200 cells/µl but still some slight benefit for those with a CD4 cell count ≥500 cells/µl